If holding current of a thyristor is 2 mA then latching current should be

0.004 A.

0.002 A.

0.01 A.

0.009 A.

Correct!

Wrong!

-

Which of following is not a power transistor?

IGBTs

TRIAC

COOLMOS

SITS

Correct!

Wrong!

-

Which of following is normally ON device

BJT

SIT

IGBT

TRIAC

Correct!

Wrong!

-

Which of the following is disadvantage of fast recovery diodes?

Recovery is only 5 µs.

Doping is carried out.

Recovery is only 50 µs.

None of these.

Correct!

Wrong!

-

A single phase full bridge inverter can operated in load commutation mode in case load consist of

RLC underdamped.

RLC critically damped.

RL.

RLC overdamped.

Correct!

Wrong!

-

Thermal voltage VT can be given by

KT/q.

Kq/T.

(K2/q)(T + 1/T - 1).

qT/K.

Correct!

Wrong!

-

Which semiconductor device acts like a diode and two transistor?

SCR

Triac

UJT

Diac

Correct!

Wrong!

-

IGBT combines the advantages of

None of these.

BJTs and SITs.

SITs and MOSFETs.

BJTs and MOSFETs.

Correct!

Wrong!

-

COOLMOS device can be used in application up to power range of

1 KVA.

100 KVA.

500 VA.

2 KVA.

Correct!

Wrong!

-

If the anode current is 800 A, then the amount of current required to turn off the GTO is about

200 A.

600 A.

20 A.

400 A.

Correct!

Wrong!

-

A power semiconductor may undergo damage due to

Low dv/dt.

High dv/dt.

Low di/dt.

High di/dt.

Correct!

Wrong!

-

The latching current of SCR is 20 mA. Its holding current will be

23 mA.

40 mA.

60 mA.

10 mA.

Correct!

Wrong!

-

Which of the following is true?

SIT is a high power, high voltage device.

SIT is a low power, high frequency device.

SIT is a high power, high frequency device.

SIT is a high power, low frequency device.

Correct!

Wrong!

-

A thyristor can termed as

DC switch.

Both AC & DC switch.

AC switch.

Square wave switch.

Correct!

Wrong!

-

Which of following devices has highest di/dt and dv/dt capability?

SITH

SIT

SCR

GTO

Correct!

Wrong!

-

A power MOSFET has three terminals called

Drain, source and base.

Collector, emitter and gate.

Drain, source and gate.

Collector, emitter and base.

Correct!

Wrong!

-

Compared to transistor, ______________ have lower on state conduction losses and higher power handling capability

Thyristor

TRIACs

Semi conductor diodes.

MOSFETs.

Correct!

Wrong!

-

Power transistor are type of

MOSFETs

BJTs

All of above.

IGBTs

Correct!

Wrong!

-

The turn-on time of an SCR with inductive load is 20 µs. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will

Turn on if inductance is removed.

Turn on.

Not turn on.

Turn on if pulse frequency us increased to two times.

Correct!

Wrong!

-

A GTO can be turned on by applying

None of these.

Positive drain signal.

Positive gate signal.

Positive source signal.

Correct!

Wrong!

-

SITH is also known as

Filled controlled diode.

None of these.

Filled controlled rectifier.

Silicon controlled rectifier.

Correct!

Wrong!

-

Which one is most suitable power device for high frequency (>100 KHz) switching application?

BJT

Microwave transistor.

Schottky diode.

Power MOSFET.

Correct!

Wrong!

-

Practical way of obtaining static voltage equalization in series connected SCRs is by the use of

one resistor across the string.

one resistor in series with each SCR.

resistors of the same value across each SCR.

resistors of different values across each SCR.

Correct!

Wrong!

-

The capacitance of reversed biased junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independent of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?

800 V/µs.

1000 V/µs.

600 V/µs.

1200 V/µs.

Correct!

Wrong!

-

A modern power semiconductor device that combines the characteristic of BJT and MOSFET is